Attachable caster unit



FIG. 1 is an expploded perspective view of the attachable unit incorporating my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a side elevational view thereof; and,

FIG. 4 is an elevational view thereof looking at the inside corner thereof.

The broken line showing of partial structure is for illustrative purposes only and forms no part of the claimed design.

The undisclosed bottom plan view is unornamented. 

The ornamental design for an attachable caster unit, as shown and described. 